A conventional method for forming carton blanks is to feed a continuous sheet of a paperboard material into a cutter-creaser apparatus in which a portion of the continuous sheet is cut and creased to form one or more carton blanks. In one commercial method, the continuous sheet comprises a composite material, of the type described in U.S. Pat. No. 4,254,173, which is incorporated herein by reference, which has a paperboard base and a plastic film outer surface. When this composite material is fed into the cutter-creaser apparatus, the paperboard base faces the lower platen and the plastic film faces the upper die. Since the plastic film outer surface will not allow moisture to escape from the paperboard base through it, there is a tendency for the composite material to curl up particularly in the cross-machine direction. This tendency to curl is increased after the cutting and creasing operations not only in the cross-machine direction but also for the portions of the flaps of the individual cartons that have been cut away on at least three sides thereof. Because of this, there is a tendency for portions of the composite material that have been cut and creased to hang up or get caught in portions of the upper die as the continuous sheet is moved in an incremental moving operation to its next location. This results in damaged carton blanks or, when serious enough, the stopping of operations to correct the difficulty. This is particularly true for relatively small cartons wherein the repeat length of each carton is less than about 12.5 inches and less than 8.5 inches in the cross-machine direction. The large number of cuts required to form a plurality of carton blanks of this size results in less overall stability of the portion of the continuous sheet being formed into cartons. Also, cartons of this size are formed from lower caliper material, such as less than 0.020 of an inch, which also results in less stability.
While the invention is described in relation to the composite material of the '173 patent, it includes other types of composite material having at least two layers, one of which is fluid containing and/or fluid permeable, such as moisture, and the other of which is a fluid impermeable layer such as a poly coated SBS (solid bleach sulfate) so as to have a fluid impermeable outer surface normally facing the upper die.